Multiple paternity in a viviparous toad with internal fertilisation.

Area of Science:

• Herpetology
• Evolutionary Biology
• Reproductive Biology

Background:

• Anurans (frogs and toads) display diverse reproductive strategies.
• Internal fertilization followed by viviparity (live birth) is exceptionally rare in anurans, occurring in less than 1% of species.
• The West African Nimba toad (Nimbaphrynoides occidentalis) is a rare example of a live-bearing anuran.

Purpose of the Study:

• To investigate the reproductive strategies and mating system of the live-bearing West African Nimba toad.
• To determine the level of multiple paternity in Nimbaphrynoides occidentalis litters.
• To explore the factors influencing paternity, such as male resource defense and mating behaviors.

Main Methods:

• Utilized eight microsatellite genetic markers to analyze paternity in litters from 12 female Nimbaphrynoides occidentalis.
• Collected field observations on male resource defense behaviors (e.g., underground cavity defense) and mating attempts.
• Statistically analyzed genetic data to assign parentage and identify instances of multiple sires per litter.

Main Results:

• Single paternity was identified in 75% (9 out of 12) of the studied families.
• Multiple paternity was observed in 25% (3 out of 12) of the families, indicating that more than one male sired offspring within these litters.
• Field observations supported the genetic findings, noting male competition for breeding sites and coercive mating attempts.

Conclusions:

• The West African Nimba toad exhibits a moderate level of multiple paternity, unusual for a species lacking specialized sperm storage organs.
• Paternity determination appears to be a result of a complex interplay between female mate choice and male reproductive strategies, including resource defense.
• These findings provide insights into the evolution of reproductive modes in anurans and the factors shaping mating systems in species with internal fertilization and viviparity.